The Legacy of the Xel'Naga
by Ivanjedi
Summary: An ancient being tries to fix the mistakes of the past through the people of the present, so there could be a future
1. Chapter 1

_**Disclaimer: **__I do not own the characters or plots from Buffy the Vampire Slayer, Stargate franchise, Starcraft, or Heroes. This is just a work of fanfiction. _

_**Author's note:** This story takes place into a universe that is a fusion of BTVS and Stargate; the only thing that is going to be used from Heroes are some of the powers of the evolved humans. The story will be roughly divided in three parts, the first one covering the Scoobies and Sunnydale, then will mostly switch to SG-1/Atlantis, and only in the very end will be the mostly Starcraft part. This will be a multi - crossover; it may contain other fandoms as well  
><em>

**Prologue**

Invisible to all, an incorporeal entity observed the remnants of the gateway that had formed by its passage into this universe, its mind filling with guilt and regret as it remembered.

It remembered how their creation, the one that held the second key to the renewal if its species, suddenly turned on them. It remembered how it panicked under the vicious assault, and had used its considerable psionic powers to attempt to escape, only to make a mistake and instead of opening a pathway to the Void aspect of its own reality, it opened a hole to the true Void between realities. It remembered all too clearly the agony from its transition, as well as that it had retained enough clarity to see the truth about what had transpired. To see that one of their own had been corrupted by the great enemy of all, the one who was there in the beginning, from whom all evil originated, and was now attempting to alter the cycle in order to pervert their people's newest incarnation into a mockery of what they truly were.

It also remembered how, desperate to leave the void, it had burst through the first reality where he had sensed the dimensional barriers had been weaker, paying no heed to what it might cause. The First had managed to exploit the rifts created by the entity's passage to send forth some of its agents, who in turn unleashed a plague that destroyed the flourishing galactic civilization.

But not everything had been lost. To the entity's utter astonishment, some of the creatures, with whom he had not been particularly impressed despite what they had built, managed to permanently transcend their physical form, becoming beings of far greater power. By observing them, the entity learned enough to do perform a similar feat, and while it did not make it virtually immortal like them, the process greatly extended its time in this reality.

But no matter the reality, everything passed to time... eventually. And the entity knew its time was coming to an end. During that time, the planet he was now observing had made more than five million cycles around its star. Several new sentient species had risen after those who gained permanent energy forms finally grew strong enough to remove the agents of the First from this reality, then had reseeded the galaxy with life. One of those new species had grabbed the entity's attention, as they were almost identical to those who had created them, and had just as much potential. Seeing an opportunity, the entity had taken advantage of its mastery over matter to create a vessel with which to send a number of specimens across the void to its home reality, to a planet looking remarkably like the one they were taken from, in a hope that they would grow strong enough to help thwart the Fallen one.

But now, as it felt its strength fading for the last time, the entity was close to despair. It had an ability to peer into the future, and had seen a possible one where its actions had created a chance for victory where previously had been none. But in doing so, a chance had been created that if the Fallen one grew strong enough in its own reality, it would be able to track these... humans to this one. If it did, it wouldn't even be a war. It would be just slaughter, as those who would be willing to protect the humans here would be, for one reason or another, too weak to succeed. If there was any hope for the future of this reality, it lay into the humans themselves.

But while they held great potential, enough to surpass even their creators, their evolution was slow. The way things were going, they could easily end up destroyed before having a real chance. This could not be allowed. If agents of the Fallen one were allowed to gain foothold in this galaxy, and by extension in the local galactic cluster, then no place in this reality would be spared from the flame, no matter how distant it was. There was only one way to go, seeing that the so called 'Ascended' were too set in their ways to make a move before it was too late, the fanaticism of their rivals, the Ori, and the controlling nature of the other 'higher beings', ruled them all out as possible allies. He needed to speed up the evolution of the species somewhere. And nowhere was a better choice than the planet they originated on. Not only the genetic diversity was the greatest there, but the planet but the unique evolutionary pressures that would help refine a greater variety of abilities than any other known species.

And if the humans did realize their potential, then there would be hope that the final legacy of the Xel'Naga would be one of life and prosperity, not death and destruction.

* * *

><p><strong>Fifteen hundred years later, 1st of October 1997<strong>

Rupert Giles let out a grunt of exertion, and picked up a large duffel bag containing odd near flat objects. He really hoped that they would help him solve the mystery Cordelia Chase had presented him with when, with her typical bluntness, she had all but dragged him to her home, to investigate the robbery that had taken place just the previous night.

Now normally, such a task would be for the police, however, the manner in which the thief had gained entrance placed the whole affair firmly into the 'supernatural' category. The Watcher had been completely baffled to discover that every door that had been locked had ended up somehow _melted._ There were bizarre shapes all over the place that resembled puddles. It was as if someone had turned the doors to water, and when that water had spilled on the floor, it had been transformed back into its original material, be that metal or wood. It made absolutely no sense! What could possibly a magic user having the ability to do _that_ want from the Chase's? It couldn't be money, despite the girl's belief that only cash and jewelry had been taken. Anyone with this kind of ability could have easily found employment on either side, employment that was at the very least paid well enough so they didn't have to resort to petty, small – time burglary.

The Watcher sighed. Even if the Chases had unwittingly acquired something mystical that was valuable enough to steal, why this way? There were many ways to steal things while making it appear ordinary, as he knew all too well, as as the Ripper he had done his share of thievery. Why do it in a way that would announce 'I was there and used magic!' like this?

The whole thing reminded the man about an incident a few years ago, with a young man living in a small town in Germany. The foolish child had dabbled in magic without supervision and somehow had succeeded into giving himself an ability to turn invisible at will... which he had then put to use, mainly for shoplifting and peeping on women. An elderly woman aware of the supernatural had seen him become visible after leaving a shop, and had confronted him, only for the teen to deny any knowledge of the occult. With the boy refusing to see reason, measures had been taken to ensure he didn't hurt anyone. Was this another amateur meddling with things better left well enough alone? Unlikely, this time the magic involved was way too complex. He had picked up several of the 'puddles', or parts of them, in hope of discovering more.

Pushing the library door open, the man grimaced. As if there wasn't big enough a problem to deal with already, in the face of Spike. He had already tried to kill Buffy once, and had come disturbingly close to succeeding before the unknowing intervention of her mother. Now, they had a thief with probably considerable magical prowess to deal with.

…...

Seeing the pained expression on the Watcher's face, Xander rushed to help him with the obviously heavy bag.

"Jeez, what do you have in here, G – man, rocks? Books?" he quipped.

"I wish." Giles muttered, cracking a smile. "What are you doing here at this time, Xander?"

"Trying to make myself useful." the boy answered, gesturing at a disassembled crossbow lying on the table. "Last night, a vamp hit it trying to get to me, and something broke."

Giles gave the boy a dark look, and Xander sighed. "OK, OK, I know that you are the one who usually fixes these things. It was Snyder. He is convinced that I can't get an A unless I'm cheating, so I had to come to redo the Physics and Biology tests. After that, I figured I'd just wait here, instead of going home and back."

"I see." The Watcher nodded. "How did this little man get assigned to this position is beyond me. A school principal is meant to work towards improving the conditions in the school and encouraging better performance from students, and not..." Giles trailed off, his eyes stopping at the mess on the table for a few moments. "Xander, may I ask what possessed you to disassemble that crossbow completely?" the Watcher said, exasperated. "The parts that _can_ break aren't that much, you should have been able to see what was wrong almost immediately.

"Err..."

"Never mind." Giles said grumpily. "Clear up the table. Put the parts in a bag and leave them in my office if you have to."

…...

Xander sighed in relief as the library door closed behind him. The Watcher was in foul mood, and the boy very much doubted that would be improved if he tried what he'd planned to try in front of the man... or the fact the boy had swiped one of the crystals Giles had used in order to try and follow the traces of magic from the bizarre objects he had brought in. There had been none the man could pick up, and it didn't take a genius to see that the Watcher was growing increasingly worried about it. And as much as the boy wanted to help with the investigation, he had found himself unable to focus on the subject, instead feeling a strong desire to try the simple - looking magic – tracing spell Giles had tried. Because of that desire, he had been unable to stop himself from taking the crystal as he had walked past it, on his way to leave a completely repaired crossbow in the weapons cabinet.

* * *

><p>As she felt the teen's hand wander, Cassandra grinned inwardly, these clubs were really like buffets for the vampires like her, who had been turned while in their early twenties. It was so easy to draw the attention of the teenagers (and the occasional older man) and make then think they were going to get lucky in the dark alleys, where she could feed on them without interruptions. And sometimes, her victims actually looked good enough to have a little 'fun' with them before draining them.<p>

With this one, however, the fun would be only for her. She pulled away from his embrace, turned to face him, and her face shifted into the vampiric visage, enjoying the sudden look of terror on his face.

"W-what are you?" the boy stammered, stepping backwards, only to realize there was a wall behind him. "Stay away from me!" he cried, raising his hands up, as if he could keep her away. Then his hands glowed.

Wait, glowed? The vampiress' yellow eyes went wide when she looked again to the boy's hands, then to his face. Every inch of skin not covered by clothes now shone with visible, reddish light, and if the look of terror on the boy's face was any indication, he was just as surprised by what was happening as she was. The glow grew brighter and brighter, first yellow, then white. Suddenly, she felt hot, very hot, and her clothes caught fire. The next moment, everything went black.

**_A/n_**_:__An unlucky vampire gets a taste of the induced radioactivity :D. Just to clarify, for any Stargate fans. Cassie Frazier is in her early teens a this point. the name is just a coincidence. _


	2. Chapter 2

_**Author's note:** Making comic book continuations of successful TV series about magic should be punishable by law :( The whole Twilight thing on BTVS 'Season Eight' sucks big time. TV series wise, their characters are defined mostly by their struggle against often impossible odds, and all of a sudden they are turned into probably most powerful beings on the planet? And there's the Charmed comic. The 'first witch' plot is just ridiculous, and they just had to bring back Prue, Cole **and** the Source. How about letting the dead, well... stay dead?_

_Now, on this fic. The rules of magic, and the pace one could grow in power in the BTVS - verse are rater loose (which, I think, is one of the things that make it so popular for crossovers, as it's very easy to fit in universes with other magical systems in.) One of the rules that is TV series canon is that use of magic requires a physical effort. For the purposes of this story, there is a limit of the amount of magic/physical effort one can achieve naturally, no matter the amount of training they receive._

_On the subject of the intuitive aptitude, its 'hunger' aspect is powerful enough to make Peter Petreli, who is always trying to save people, attack his mother for her power. However, it is never made quite clear exactly what triggers the hunger, as unless it was Chandra Suresh who activated Sylar's power, he possessed it since at the very least his teens, if not his whole life, and had a pretty normal life before finding out he was really different. Also, the limitations Sylar's power, for example in regard of electronics, is unclear. There are rules I'm going to follow about the intuitive aptitude:_

_ has to be some kind of system to whatever is being studied. (obviously) _

_ ability would help understand a system from a book. However, it would not be as fast as a direct observation, and the 'hunger' would not be as strong._

_ 'hunger' for an an ability that is observed will always override the desire for one that has been read about._

_ the intuitive aptitude to work, the user has to have at least some idea what to look for (like Sylar knowing that the abilities of the evolved humans come from differences in their brains) or the ability to trace what makes the system work(Electricity for electronics, direct observation for watch mechanics, etc.)_

Rupert Giles had seen many strange things in his life, even for a Watcher assigned to guide an active Slayer. But he couldn't help thinking that witnessing Xander take a bag containing the parts of an old mechanical alarm clock, and put it together in less than thirty minutes before his eyes had to to be one of the strangest.

"Interesting." the man commented while polishing his glasses. " I seriously doubt that even an expert on mechanical clocks could assemble one this fast." Giles scratched his chin in thought. "You said you _realized_ something was out of the ordinary when you repaired it for the first time. That means it had happened before without you noticing. When?"

"Well...There was the crossbow couple of days ago. The one I took apart to the smallest pieces, remember? It was broken anyway, so I didn't think much about taking it apart, and the crossbow isn't that complex to begin with."

"Understandable mistake to make." Giles nodded.

"Yeah, probably. Then there was the magic detection trick I learned to do." Xander grimaced. "I can't believe I managed to ignore _that_ for any amount of time."

"Magic detection thing, you mean what you saw me use? You managed to do it after only seeing it once?" the Watcher exclaimed incredulously. The boy shook his head.

"No, I mean, you don't need to be the sharpest tool in the shed to realize there was more to it than moving crystals about. And you were already mad at me about the crossbow, and busy with something else, so I seriously doubted you'd let me search through your books for the instructions, never mind help me if I asked you. For all I knew, there was a chance you would forbid me to search instead. So I left, taking one of the crystals with me, and found the necessary instructions elsewhere."

"Where?" Giles asked, not at all happy at what he was hearing. Magic was not something to dabble into lightly. He needed to know if there was a source of knowledge of the occult that was easily accessible.

"You do remember Miss Calendar's friends? The ones who helped with stopping Moloch?" the Watcher nodded. "Well, they are not the only ones to have Web sites on the supernatural. I may not be as good in finding info as Willow is, after a few hours of searching, I found what I needed. It helped that I had watched you, and had at least some idea what to look for."

"What?" The Watcher exclaimed incredulously, finding it very hard to imagine that _anyone_ would be irresponsible enough to put real instructions for magic for everyone to see; granted, most of those who would see it would laugh at it, and even with the instructions followed to the letter, magic simply wouldn't work for someone who didn't believe in it, but still... The man sighed. "I take it something went wrong, or at the very least not exactly as expected. What was it?"

"The spell itself worked perfectly, even though it took me several tries to do it right. I mean, I could feel the magic flow, but nothing reacted as expected. It isn't like I have anything magical in the basement back home. The strange thing was, I was able to understand exactly how magic had to be manipulated for the purposes of detection by doing the spell just once; I practiced a bit, and less than an hour later, I could copy the magic manipulation for detection without the crystal."

Giles scratched his chin; this seemed to match the ability to learn things at a seemingly impossible pace Xander had described (and showed the results of) earlier; the boy had told him he had learned the workings of the mechanical clock (and fixed it) by simply disassembling it. That the ability would work _on_ magic meant there was no way it could _be_ magic itself; but while a part of him wanted to have Xander test its limits, as used properly this could be incredibly useful, the Watcher knew he had to find out exactly how had Xander attained such a gift. Even if the ability wasn't magical in nature, this was no guarantee it wasn't magical in origin, and the man knew that the beings who could grant boons on humans _always_ did so for a price. Xander would not make a deal with a demon; that much Giles was certain. But there were other possibilities that could have just as unpleasant consequences, and Sunnydale was no place to take unnecessary chances. Luckily, a boon granted by a creature of magic always left a mark.

* * *

><p>Xander's face twisted into a scowl as he dropped into his bed, feeling as if he'd run a marathon today, while he had done nothing of the sort; he had spent most of the day, that was, after classes, in the school library with Giles, trying to figure out and then practicing a single spell from a book the Watcher had given him. No doubt Giles wanted to keep an eye on him, not fully trusting his mysterious gift.<p>

And mysterious it was; despite the all four of them researching any possible sources his ability could have originated from, they had come with nothing, not a single clue. Giles had even gone as far as having him strip into his office, then casting several spells meant to reveal involvement from an otherworldly being, as well as (on Buffy's insistence) a number of general exorcism rituals. All of those the boy could now perform expertly, as, unable to contain his curiosity, he had used used the magic tracking ability he already possessed, and was thus able to follow the manipulation of magic the Watcher was doing. It was just like taking the old clock apart; he could somehow figure out exactly how each spell worked, so casting them himself turned out to be ridiculously easy. So easy, in fact, that after a few casts he no longer needed the crystals/herbs/other stuff described to be needed. (Giles explained to an incredulous Willow that under ideal circumstances, magic could be performed by strength of will alone; physical objects, when used, were meant to ease the caster into shaping magic for the desired purpose)

Xander sighed. When Giles had put an end to the research session, admitting that there was no reason he could find for him _not_ to use the weird ability to figure things out, he had hoped to learn a few spells that were useful in a fight, and thus be more than moral support for Buffy in battle. It was humiliating enough that he'd had to be the messenger boy, who had been sent to call the one who _could_ help during the mess with Spike. However, it was not to be, as the magic he had used trying to master the spells he had 'copied' from Giles had been enough to tire him, making the Watcher realize that his affinity for magic was extremely weak. Which, in turn, meant that even with the extraordinary control he was able to achieve, use of magic in battle on his part could only be something done when everything else had failed.

It wasn't helping that (as they discovered over the next few days) when trying to cast a spell by following instructions from a book, he was not learning any faster than anyone else would have; in one instance, in order to compare, Giles had him and Willow try a simple spell that created a bright flash in front of the caster, providing the instructions at the same time. Despite the fact this was the very first spell Willow cast, (she had read about magic, but not tried it before) she managed it before he did, even it was only a flicker. It was only after she demonstrated it that he managed it, unable to resist the temptation to copy it. Then, unsurprisingly, he had quickly mastered it.

The boy glanced down at the old clock that he had kept for the sole reason of being a present from his grandfather and namesake, even after his father had broken it in a drunken rage a few years back. Giles would be absent from Sunnydale for the next few days, and had left the key to his office, and the books within, to Miss Calendar, with instructions not to allow them access unless there was an emergency. Perhaps it was a good time to see what else this wacky gift could help him learn that wasn't related to magic, as it was not guaranteed that it wouldn't just vanish as suddenly as it had appeared. Chances were, even if it did vanish, the knowledge he'd gained with it would remain. He would be a fool not to make full use of it. Tomorrow morning, he had to join the class for a visit to the museum, as a part of the school's student exchange program. After that, not counting school, he'd have a few days all to himself.

* * *

><p>Suppressing an urge to kick something in frustration, Willow turned to leave. The dance was a bust, that was for certain. The only thing she had accomplished by coming here tonight was to get insulted by Cordelia Chase, although this had been somewhat negated by the chance to see Ampata, the exchange student staying at Buffy's, try to steal the cheerleader's date in the short time Cordelia had taken to deride her.<p>

The redhead sighed, with Xander taking a lot more interest in learning lately than he did before, (Previously, he bothered to study only if he wasn't sure he could get a passing grade) she had been hoping that the extra time they ended up spending together in the library would help the boy see her as something more than his best friend and study buddy. Her hopes had only increased when Xander had failed to comment on the idea of having Buffy play host to a _male_ exchange students, (The redhead had been expecting Xander to become jealous) and even more after Xander had completely ignored Ampata even though one had to be blind not to see she was flirting with him in school. But it seemed that she had read the signs completely wrong, as the boy hadn't even bothered to show up for the dance.

Then again, it had only been a week since Xander had become more interested in studying, and now that he seemed to be over Buffy, she finally had the chance to spend more time with him. If she gave him a little more time...

Seeing that there was still a bit of sunlight left, she made her way home, narrowly missing the Slayer's arrival, in near panic, at the dance, as well as Buffy's discovery of Ampata's half – mummified body, which had been somehow turned to glass.

"Turned to glass?" Giles exclaimed incredulously as the teenagers filled him in about what had transpired in his absence.

"Everyone else thought it to be some kind of weird decoration." Buffy said. "One nobody remembered bringing in."

"Were there any witnesses to the transformation?" The Watcher asked, ignoring the Slayer's slight snark at the Sunnydalers' talent of rationalizing everything supernatural.

Willow shook her head. "None we know of. We moved the body and locked it up at Miss Calendar's place, so you could have a look at it." the redhead glanced towards the man's office. "We found nothing that could explain how it happened, just that for all we know, Ampata is only a wacky glass statue now."

"One of the wacky things nobody can figure out lately." the Slayer muttered, shooting Xander a look.

Giles stifled his annoyance at his charge's attitude. Buffy had not been happy that he'd ceased looking for possible origins of Xander's mysterious gift; the boy's behavior had changed quite drastically because of it, and because of that, she firmly believed he had to be 'fixed'. The Watcher could see where her hostility was coming from; the last time the boy had acted this differently compared to what they had come to see as a norm for him, it had been a near disaster, with her in the middle of it. But while her paranoia was not without foundation, being stubborn about it only made her look like a particularly petulant child. It wasn't like there was anything he could do unless he had at least some idea where Xander's gift had come from, and he had none.

He really hoped her attitude would change after he explained that he had stopped searching because he had exhausted the possibilities described in the books he had on hand, not because of giving up; the ability Xander had displayed was just too strange to do that. In fact, one of the reasons to make the journey he'd just returned from had been to consult with one of his colleagues working here in the States on the matter.

But before dealing with the potential problem that was Xander, he had a... glass statue to check out, and then destroy, just in case. The Watcher shook his head; it was almost certain that the individual who had transformed the killer mummy into it was the one responsible for the thievery at the Chase's. It was extremely unlikely that a second mage prone to such ostentatious use of magic would decide to come in Sunnydale in less than two weeks, even with this bloody town attracting the weird in droves.

* * *

><p>Larry Blaisdell growled as the material of his spare bike chain changed before his eyes... to wood. Why couldn't he get it right? He already knew he could change stuff from one material to another, but much to his irritation, didn't seem to be able to properly control what he was turning stuff into. That was the reason he avoided touching one of his old textbook, which had been torn enough to belong in the garbage bin, that was if it weren't for the fact it he had managed top transform it into gold after checking how that looked like on his grandmother's old earrings. Accidentally changing it into some other material would just not do.<p>

The jock was aware that what he had found himself able to do was _not_ natural, after all, while not exactly a model student, moron he was not. He understood all too well that he could tell nobody about this, or he risked ending up being turned into some mobster's private gold mine, or worse, being experimented on in some laboratory. But it didn't mean he couldn't make use of this himself... if he could get a hang of it. Unfortunately, remembering clearly using this ability for the first time was not helpful.

Larry shuddered; seeing that walking corpse's skin shrivel up and dry before his eyes was something he would probably remember for the rest of his life. He had been to the loo, and had been walking back to the dance when 'she' had thrown herself at him. If he wasn't interested in boys (not that he would ever admit _that_ to anyone) he would have probably not complained. As it was, he had held her back for a few moments... that was untuill she had begun to change before his eyes. From shock, he had lost his grip, only to instinctively raise a hand before his face when 'she' had tried to kiss him. It had been that touch to turn her to glass somehow.

Now only if he could master the ability, so he could do that reliably... and with gold instead of glass.

_**Author's notes: **Poor Giles, he will be looking in the wrong direction for a while. On the other hand, Larry is getting rich :) His ability is one of my own creation, based on the alchemy from Heroes_

**Transmutation** – _the user 'memorizes' the structure of anything he touches, and can will an object he touches next to be changed into the first object's material. There is no limit of how many atomic/ molecular structures may be memorized, but the 'memory' only lasts an hour. Mass is not changed by the transmutation. It can copy the structure of alloys, as well as simple organic molecules like hydrocarbons, but not living tissue._

_In conclusion, now that the stage has been set, it's time for the real fun to begin :) There will be human deaths on Xander's head because of the Hunger, but not exactly in the same way as Sylar._


End file.
